In the past brewing devices such as, for example, coffee makers have included heat distributor plates, hereinafter referred to as warmer plates, for keeping the freshly made coffee contained in a glass vessel hot. A disadvantage of these devices is that the coffee quickly looses its freshly brewed quality and becomes stale within a couple of hours. A further disadvantage of these devices is that under conditions of frequent handling the glass vessels are subject to breakage when brought into contact with warmer plates which typically are made of metals or alloys thereof.
The breakage problem is highlighted in U.S. Pat. No. 3,145,708 issued Aug. 25, 1964 to Kenneth J. Fischer. This patent notes that a glass or ceramic coffee maker vessel tends to crack and break along its bottom area that includes the portion thereof that is directly subjected to the heating source, and teaches the use of a brewing vessel protector. The protector includes a metal protector cover, cup or cup adapted to space the glass vessel from direct contact with the metal warmer plate. The cup is constructed to snap on to the glass vessel. Thus, it can be readily removed from the glass vessel for cleaning or subsequent use with another vessel during the cleaning of a previously used vessel. Those persons skilled in the art desiring further information about the device are referred to the patent.
A bun warmer or potato baker is known which includes a handled body portion having a top surface. The top surface includes raised, eccentric rings spaced one from the other to provide flat surfaces therebetween. The flat surfaces include an outer surface having apertures grouped in pairs between raised louvered vents; the inner surfaces including only the louvered vents. In operation the foodstuff is placed on the rings and placed on a warmer. Hot air rises vertically through the apertures and louvered vents. The latter causes turbulence which distributes the heat for uniform heating of the foodstuff. This device is disclosed in detail in U.S. Pat. No. 4,446,776 issued May 8, 1984.
Another known cooking device includes an apertured corrugated plate. A food supporting rack is supported by legs above the corrugated plate. A pad of heat non-conducting material having a thickness considerably less than the space between the rack and plate is positioned over the plate. The pad covers a portion of the apertures to diver the heated air currents outwardly so it will enter a hood adjacent the periphery of the plate. In this manner the bottom of the article to be cooked will not be cooked too rapidly in comparison with the rest of the article and be burned before the rest is done. This device is disclosed in U.S. Pat. No. 1,685,829 issued Oct. 2, 1928 to S. Sauvage. Other known devices are similar to those described above. A heating utensil which includes fins on the underneath side of a bottom surface for heat distribution is disclosed in U.S. Pat. No. 2,213,378 issued Sept. 3, 1940 to M. E. Benesh, and a radiant toaster having a base which includes an outer flanged down ring and a radiant center of tongue type openings for lengthening the heating path is disclosed in U.S. Pat. No. 2,546,795 issued Mar. 27, 1951 to J. W. Stechbauer.
The essential difference between the prior art devices and the device of the present invention is the provision of a warmer plate cover for a brewing device for providing uniform temperature on the bottom of the vessel consistent with the temperature of the remaining portions of the vessel to uniformly heat the fluid content of the vessel thereby alleviating the development of burnt and stale coffee taste characteristics in the fluid and glass breaking stresses in the vessel.